1. Field of the Invention
The present invention relates to a trocar assembly and, more particularly, to a trocar assembly suitable for use in laparoscopic intra-corporeal operations.
2. Description of the Prior Art
In recent intra-corporeal surgeries, laparoscopic or endoscopic surgeries have been performed to avoid cutting the skin over wide ranges. Such laparoscopic surgeries are generally performed by piercing a Veress needle into the abdominal cavity of a patient in place, insufflating an insufflation gas (generally, carbon dioxide) into the abdominal cavity, removing the Veress needle from the abdominal cavity after the abdominal cavity has been insufflated sufficiently, introducing a trocar fitted with a rigid sheath with a diameter of 5 to 12 mm into the abdominal cavity through the same site of the puncture, and then introducing a laparoscope into the abdominal cavity through the sheath to perform an intra-corporeal operation. In such intra-corporeal operations, however, there is a fear that any internal organ in the abdominal cavity may be injured by a piercing edge of the trocar during insertion into the abdominal cavity.
To solve such a problem, it has been proposed to provide a protective sleeve on the trocar so as to cover a piercing edge of the trocar or to receive the trocar when the piercing edge of the trocar has passed through the peritoneum. Such a trocar fitted with the protective sleeve is adapted to penetrate the abdominal wall or peritoneum by pushing it in its longitudinal direction, and the protective sleeve serving as a safety mechanism of the trocar is so designed as to perform its function to cover the piercing edge of the trocar just when the piercing edge of the trocar is completely introduced into the abdominal cavity.
During insertion, the trocar is advanced by the external force applied thereto in the direction facing to the internal organs, notwithstanding the piercing edge of the trocar which has been protruded from the protective sleeve. Thus, it is difficult to prevent the internal organ completely from being injured by the piercing edge of the trocar even though the abdominal wall (peritoneum) has been spaced from the internal organs by insufflation.